Field of the Disclosure
The present disclosure relates to laser processing and more particularly, to multiple-beam laser processing using multiple laser beams with distinct wavelengths and/or pulse durations.
Background Art Discussion
Lasers have been used to perform a wide range of material processing to alter a material in some way, for example, by ablation, melting and annealing. In particular, the material may be heated by the absorption of laser energy until the material evaporates, liquefies, or otherwise changes its state or structure. Laser processing may be difficult for certain types of materials such as materials that are transparent or reflective to the laser. Such transparent and reflective materials may not absorb the laser light at certain wavelengths sufficiently for the laser energy to alter and process the material. Laser processing of transparent materials such as alumina and sapphire, for example, is difficult using a laser operating at a wavelength around 1064 nm because most of the laser light transmits through the material instead of being absorbed by it.
When using a laser to drill holes in transparent materials, for example, the laser beam may be delivered to the target but a hole is not created if most of the laser passes through the material without sufficient absorption. The pulse energy and peak and/or average power of the laser may be increased to ensure processing of these materials, but the increased energy and power is inefficient and often results in an undesired increase in the size of the holes being drilled and a lower quality of the holes. Other techniques have required a coupling enhancer such as a coating layer to enable processing of transparent materials, which may not be desirable.
Other types of non-absorptive materials, such as reflective materials, may also be difficult to process using lasers. Welding reflective materials such as copper with a 1064 nm IR laser, for example, often requires a high enough pulse energy/power to overcome the reflectivity of the material. These high powers can make it difficult to control depth of affectation, for example, when micro-welding thin foils. Thus, laser processing applications sometimes face the unique challenge of using higher power lasers to perform the desired processing but without causing residual damage.
Accordingly, there is a need for a method for enhanced laser processing, particularly for non-absorptive materials, with lower pulse energy/average power and higher quality.